The Unknown War is a military history book written by Hienadz Sahanovich. It describes the events of the war between Tsardom of Russia and the Polish–Lithuanian Commonwealth in 1654-67. The war has become known as a part of the "Deluge", a series of military conflicts that overwhelmed the Polish–Lithuanian Commonwealth in the middle of the 17th century which included the Khmelnytsky Uprising, the Swedish invasion, and the Russian invasion among others. Source: Wikipedia (en)